1. Field of the Invention
This invention relates generally to AC electric metering systems including voltage and current sensing transducers for applying signals responsive to the current and voltage parameters of an electric energy quantity, and more particularly, it pertains to electronic circuits for measuring power, voltage and current of extra high voltage transmission lines using magneto-optic current transformers for sensing current, and a capacitor circuit for providing voltage signals, voltage signals being proportional to the raate of change of voltage with respect to time.
2. Description of the Prior Art
The Faraday effect has been defined as existing when a plane polarized beam of light passes through certain transparent substances along the lines of a strong magnetic field, the plane of polarization of the emergent light is different from that of the incident light. The Faraday effect has been employed in the measurement of magnetic fields. However, its use for monitoring parameters of an electric current is less common, because the magnetic field arising from the current flow in an arbitrary circuit generally has a spatial variation. Suffice it to say, Faraday effect current sensors provide a high degree of linearity, good sensitivity, and excellent voltage isolation.
Examples of prior art patents generally disclosing the use of devices for AC electric energy measurement include U.S. Pat. Nos. 3,746,983; 4,077,061; 4,182,983; 4,232,264; and 4,413,230. It is the purpose of this invention to show how Faraday effect current sensors can be incorporated into a measuring system for monitoring power, voltage, current on an extra high voltage transmission line using a magneto-optic current transformer for current sensing and a capacitor to provide a signal representative of the voltage which signal is proportional to the rate of change of voltage with respect to time.